Pneumatic door-check



(Model.) 3 Sheets-Sheet l.

G. GEBR. PNEUMATIG DOO-B.w CHECK.

'Patented Peb. 9, 1886.

(Model.) 3' Sheets-Sheet 2.

G. GEBR. PNBUMATIUDOOR CHECK.

No. 335,575. Patented 1155.9, 1885.

3 Sheets-Sheet 3.

(Model.)

G, GEBR. PNBUMATIG DOOR CHECK.

Patented Feb. 9, 1886.

UNITED STATES PATENT EETCE.

GEORGE GEER, OF PETERBOROUGH, NEV HAMPSHIRE.

PNEUMATIC DOOR-CHECK.

SPECIFICATION forming part of Letters Patent No. 335,575, dated February9, 1836.

Application filed February 23, 1884. Serial No. 121,647. (Model.)

To all whom, it may concern.-

Be it known that I, GEORGE GEER, of Peterborough, New Hampshire, haveinvented certain new and useful Improvements in Pneumatic Door-Checks,of which the following description and claims constitute thespecification, and which is illustrated by the accompanying three sheetsof drawings.

This apparatus closes a door gently by means of the joint operation of ascroll or other spring acting upon certain devices,hereinafterdescribed, and a partly-confined column of air, which acts as a cushionto moderate the action of the spring.

Figure 1 in the accompanying drawings is a plan view of the apparatus asattached to a door-case and a closed door. Fig. 2 is afront elevation ofthe bracket 24, by which the apparatus is attached to the door. Fig. 3is a plan view of the apparatus as attached to a door-case and an opendoor. Fig. 4 is a central vertical longitudinalsection oftheair-cylinder13. Fig. 5 is a central vertical longitudinal section ofthe right-hand part of the piston-rod. Fig. 6 is a cross-section of thepiston-rod on the line A A of Fig. 5. Fig. 7 is a front elevation of theapparatus attached to a door-case and an open door. Fig. 8 is a view ofthe piston and piston-rod and their connection.

9 is a casing screwed to the door-case just above the door. It supportsthe upright pivot 10, upon which the journals 11 and 12 of the cylinder13 are tted to turn. The upper and lower walls of the casing 9 arefurnished with bearings for the arbors of the eccentric segmental gears14 and 15,. both of which turn within that casing. The gear 14 is workedby a coiled spring, 16, the inner end of which is attached to the arborof the gear, and the other end of which is attached by the pivot 17 tothe casing 9. The gear 15 is one piece with the arm 18. That arm isprovided with the hbrackets 19 and 20, and those brackets are connectedby the rod 21. Upon that rod the traveler 22 reciprocates as it turnscorrespondingly upon the pivot 23, which constitutes the upwardprojection of the bracket 24. The stud 25 projects up and from the arm18, and is itself surmounted by a pivot, 26. Upon that pivot theleft-hand end of the piston-rod 27 turns. That rod is not rigidlyattached to the piston, but has a slight longitudinal play therein. Thepiston is composed of the shell 28, furnished with the flange 29, and ofthe gland 30, which, being screwed upon the shell 28, compresses thepacking 31 against the inner circumference of the cylinder 13. Thepiston-shell 28 is perforated axially for the ad.- mission of thepiston-rod. Near the right` hand end of the perforationit becomesabrupt- 6o ly smaller, thus furnishing an annular shoulder, againstwhich the conical end of the piston rod presses when making its inwardstroke. The shell 28 is also provided with the diametrical perforation32, in which the crossstud 33 of the piston-rod reciprocates. It is thisreciprocating which allows the longitudinal play of the piston-rod inthe piston. rlhe shell 28, which forms one of the walls of theair-cushioning chamber, is also provided with the vents 34 and 35, orone of them. Both of these vents are adjustable in respect to the extentof their outer openings, but on variant plans. The outer end of the vent34 passes through the plug 36, which plug is composed of lead or othersoft metal, and the opening in which may therefore be readily lessenedin extent by a slight blow of a hammer, or readily increased in extentby the action of a reamer inserted and worked therein. The outer end ofthe vent 35 is partly closed by the conical end of the screw 37, and theopening in that end of that vent may therefore be increased ordiminished by raising orlowering the screw, respectively. rlhepiston-rod does not require an air-tight tit where it passes through theleft-hand head of the cylinder, and, indeed, that cylinder-head isfurnished with one or more perforations, 38 and 39, in order to providefor free communication between the external air and the air in theleft-hand end of the cylinder. The right-hand end of the piston-rod isprovided with one or more grooves, 40 and 41, for a purpose to beexplained hereinafter.

The mode of adjustment is as follows: The casing 9 is screwed to adoorcase just above the door and at such a position laterally as thatits left-hand end is on a line with the hinges of the door, orapproximately so. rlhe bracket 24 is then screwed to the upper border ofthe door in such a position that the travelerl 22 is nearly at theright-hand end of 21- when thev door is'opened. The left-handcylinder-head is then uuscrewed from the cylin-V der and slipped alongthe piston-rod, and the vcntis then adjusted and the cylinder-headpartly screwed in place, and the door allowed to close, so as to testthe strength. with which the air-cushion resists the action of thespring.'A If that resistance is too great, the vents 34 and 35, or oneof them, are enlarged; or, if that resistance is too little, they arelessened in egg tent by the means heretofore explained in that behalf.Then the cylinder-head is screwed into place again, and the adjustmentAis com-v plete. Y

The mode of operation is as follows: As the door is opened, the arm 18of the gear 15 is forced outward with the door, the traveler 22 slidingalong the rod 21 to permit the opera tion. At the same time the gear15,meshing with the gear 14, winds up the spring 16, and t-he piston-rod 27is drawn out, so as to bring the piston into the position shown in Fig'.4. This drawing out of the piston does not create any vacuum in thecylinder, because air may freely pass through the grooves 40 and 41, andthence between the conical end' v`of the piston-rod and the annularshoulder in the axial perforation in the piston, and thence into thecylinder itself. When the door is released frorn the force which openedit, the spring 16, operating upon the arbor of the gear 14,and thus uponthat gear and upon the gear 15 and the arm 18, will quickly close thedoor. This movement is moderated, however, by the action of the pistonand cylinder, and in the following manner: The inward movement of thearm 18 soon forces the piston-rod into the piston, so that the conicalend of the rod presses against the annular shoulder in the axialperforation of the piston, thus closing the air channel through thatperforation. Then the pistonrod forces the piston inward in thecylinder; but inasmuch as the vents 34 or 35, or both of them together,furnish but small air-channels for the escape of the air in theright-hand end of the cylinder, that movement is necessarily retarded bythe partly-confined column of air, and in return it retards andmoderates the shutting of the door.

The eccentric shape of the gears 14 and15 enables a given force in thespring 16 to exert about four times as much power just before the dooris fully closed as it exerts just after the door begins to close. Thisadvantage is not suddenly acquired, but gradually grows with themovement of the door, and thus compensates for the graduallydiminishingforce of the spring as it uncoils.

In doorchecks of this class it is important that the valve which cutsoff the ow of air from one side of the piston to the other shall actvery quickly upon the return-stroke of theV piston, and thereby confineas large an amount of air as possible, so as to obtain the bestcushioning effect.

As heretoforev constructed, the -yalves of pneumatic door-checks5so farasI am aware, have been those thata're closedl by the press. ure of theair upon the return movement of the piston, and in many cases the airwould not so act until the piston had moved quite a distan ce on itsreturn-stroke, and'consequentl y a sufcientamount of air would not beconfined in front of the piston to properly cushion the door. If thepiston-rod is moved slowly on the return-stroke, the valve will notclose so quickly as when said rod, by reason of strong drafts of air orfrom other causes, moves more rapidly,` and consequently thecushioning-power is variable.

In my door-check the, closing of the valve does not depend upon pressureof the air,

as the friction of the piston upon the cylinder holds it stationary whenthe piston-rod begins to return, and so. soon as the piston-rod hasmoved a distance equal to the play of the cross-stud 33 in thediametrical perforation 32 the valve is closed; in other words, the

valve which confines the air is always closedv upon a given movement ofthev piston-rod, whether said rod is returned slowly or otherwise.

I am aware that aA prior patent shows a pneumatic door-check consistingof arpivoted cylinder, a piston fitted thereto, a springactuated arm,and a bracket for connecting one end of said arm with the d oor in suchmanner as to permit said arm to slide upon the bracket; also, thatanother. priory patent shows a door-spring consisting of a frame, atorsional wire spring,vtwo eccentric gears, and an arm connected to oneof said gears, with the end of said arm provided with a frictionroller.Both of said'prior devices are hereby disclaimed.

I claim as my inventio'n- 1. The combinationof the casing9, spring 16,the eccentric gears 14 and 15, the arm 18, turning on the same axis withthe gear 15, the cylinder, and` the piston, the latter being pivoted tothe arm 18 at a point between the axis of said arm and the endwhich .isconnected or designed to be connected.y with the door, substantially asdescribed, and for the` purpose specified.

2. rIhe combination. of theA spring-pressed angular arm 18, pivoted uponan axis, as that of the gear 15, the cylinder set paralled to thelongest end of said angular arm when in theirv nation of a cylinder andVpiston-rod having.

the longitudinal grooves with means for operatively connecting them to adoor and its jamb, and a pistonwhich fills the cylinder,

having an annular shoulder in its axial bore' and fitted upon thegrooved end of the pistonrod, with the latter having a slight longitndiAIOO iro

nal play thereon, said grooves and axial bore forming an air-passagethrough the piston when the door is being opened and the piston is drawnbackward, which passage is closed on the return movement of the door andpiston by the end of the piston-rod acting against the annular shoulderin the piston, substantia(l]y as described, and for the purpose specie4. The combination of the spring, the eccentric gears 14 and 15, the arm1S, connected to one of said gears, and having the rod 21, the bracket24, traveler 22, pivoted to said bracket and fitted upon the rod 21, thepist0n-rod cylinder, and means for pivoting the 15 cylinder,substantially as described.

GEORGE GEER. Vitnesses:

F. G. CLARKE, M. L. MORRISON.

